Introduction to DC motors

What is DC Motor

Direct Current Motors or DC motors, in short, is operated by direct current, converts electrical energy into mechanical energy. DC motors can provide variable torque and speed according to our needs. In this article, we will discuss the main components of DC motor, its working principle and how different components work during operation.

Operational Principle of DC Motor

DC motor works on the principle of simple electromagnetism that,

“A current-carrying conductor experiences a force when placed in magnetic field perpendicularly, the direction of this force is perpendicular to both current-carrying conductor and the direction of the field”.

According to Fleming's left-hand rule, the direction of force is perpendicular to both the magnetic field as well as electric current. If the thumb, index finger and the middle finger of the left hand are extended perpendiculars to each other, the middle finger shows the direction of the magnetic field. The index finger represents the current direction, and the thumb demonstrates the direction of forces acting on the conductor. This is shown in the figure below.

Construction of DC Motor

Two main components of the DC motor are stator and rotor(armature). The Armature is the rotating component and is connected to the DC supply. The stator is the stationary part.

Stator

The stator of the DC motor consists of either electromagnetic or permanent magnet windings. It generates a stationary magnetic field around the rotor.

Armature

The armature of DC motor is placed between the south and north poles of an electromagnet or permanent magnet. It is made of electric windings.  The armature is connected with a constant DC power supply. When external current is applied to these windings, a magnetic field is created. The rotor rotates because magnetic poles generated by the rotor field are attracted to opposite poles generated by the stator. The windings of the armature can be concentric windings, split windings, lap, etc. Armature core is made from silicon steel stampings. A thin paper or coating is used as an insulation between each stamping. The armature consists of commutator and brushes.

Commutator

A commutator is a device that converts AC induced in the motor armature coil into DC due to which continuous motion of the DC motor can be maintained. Commutator directs the flow of current and thereby the direction of the magnetic field. It is mounted on a rotating shaft of DC motor and is usually made of the copper segmented sleeve.

Brushes

Brushes transfer current from rotating part of the motor to external load which is usually stationary. They are rectangular and are made of carbon. Different parts of the DC motor are shown below in the figure.

Working of DC motor

The Working of DC motor is built on the linking of rotor and stator fields. A magnetic field is produced when current is passed through armature windings. This magnetic field opposes the magnetic field produced by permanent magnets of the stator. As a result of which torque is produced by the action of these opposite magnetic forces, which in turn rotates the DC motor. It is clear from Fleming's left-hand rule that force on each conductor tends to rotate the armature in the counter-clockwise direction. These forces add up to produce net driving torque which rotates the armature.

DC motor consists of large number of armature coils or windings which are kept under impact of magnetic field. The greater the number of coils higher will be the motor speed. Current enters through north pole into the armature coil and move outwards through south pole. The direction of torque acting on coil remains the same by the movement of coil from one brush to another which changes the polarity of coil.

There are large number of armature coils because motor stops rotating when armature coil is perpendicular to magnetic field. For this problem not to occur DC motor has a number of armature coils. When one coil is perpendicular to field the other coil induce the torque so, the motor rotates continuously.  The speed of DC motor can be varied by connecting them to gearboxes or gear trains. By doing so output speed of DC motor can be decreased but output torque would increase. This makes them suitable for automotive, electronic and robotic applications which will be discussed in another article.

DC motor consists of large number of armature coils or windings which are kept under impact of magnetic field. The greater the number of coils higher will be the motor speed. Current enters through north pole into the armature coil and move outwards through south pole. The direction of torque acting on coil remains the same by the movement of coil from one brush to another which changes the polarity of coil.

Conclusion

DC motor works on electromagnetism principle and by doing utilizing the magnetic fields and proper arrangement of stator and rotor windings, electrical energy can be converted into mechanical energy.

Here we are in Ke Gu Motor, we focus on DC motor producing and provide you with a better power solution.